Charged earlier this month, Ridgway pleaded guilty Friday afternoon to aggravated first-degree murder as required by a plea agreement struck in 2003 following his arrest. Already serving 48 life sentences -- one for each woman he was convicted of killing following the plea deal -- Ridgway was again sentenced to life without the possibility of parole.

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Marrero -- a 20-year-old mother working, like many of Ridgway's victims, as a prostitute -- was last seen in SeaTac in December 1982. She was found Dec. 21 in an Auburn ravine, about 100 feet from the location where a woman known to have been killed by Ridgway was found during the search that followed his lengthy confession.

The agreement and subsequent interviews with police enabled prosecutors to bring 48 aggravated murder charges, closing the bulk of unsolved King County slayings thought to be Ridgway's doing.

During a lengthy police interrogation following the 2003 agreement, Ridgway admitted to killing Marrero and other Seattle-area women but was not charged in those disappearances. Prosecutors were not convinced Ridgway was being truthful or -- as he admitted -- able to remember all the women he killed.

Ridgway eventually led investigators to the remains of four missing women but could not remember where he'd left Marrero's body or give an accurate description of her.

"I killed so many women, I have a hard time keeping them straight," Ridgway said in a statement he wrote for the court.

On Friday, Ridgway -- clad in belly chains and a blaze orange jumpsuit -- began apologizing to the Marrero family but was shouted down.

"Shut your mouth," a man yelled. "Shut your (expletive) mouth."

The outburst silenced Ridgway, and Roberts imposed the sole sentence available to her.

Before she did so, though, Roberts remarked that she is usually a judge of few words, but had a few for Ridgway.

Roberts said she found herself unable to hold out any hope for Ridgway's humanity.

"I can find no compassion," Roberts said. "Instead, my heart is completely filled with sympathy for the family of Rebecca Marrero, and despair that a person is capable of such a crime."

Marrero's disappearance was ultimately investigated by the Green River Task Force. Police said Marrero was friends with Debra Estes, another woman Ridgway admitted to killing.

The contentious plea deal struck by former King County Prosecutor Norm Maleng required Ridgway to admit guilt in all his King County killings. In exchange, Maleng agreed not to seek a death sentence, so long as Ridgway pleaded guilty to the charges.

Additional charges elsewhere in the state or country, which are not precluded by the agreement, have not followed. The serial killer remains a suspect in dozens of other disappearances, but has yet to face charges elsewhere.

Announcing the new charge against Ridgway, King County Prosecutor Dan Satterberg noted that the plea deal was aimed at the families of dozens of women thought to have been killed by Ridgway, but which had little evidence.

"It wasn't about what Gary Ridgway deserved," Satterberg said. "He deserved no mercy. He deserved the death penalty.

"In the end it was about what the families deserved. We knew that the single-minded pursuit of the death penalty would come at a great cost, the cost of the truth of the disappearance of dozens of known victims, disappearances that continued to haunt their families."

Ridgway led investigators to the remains of Marie Malvar on Sept. 28, 2003 in the same area where Marrero was found. Ridgway was convicted in the Malvar homicide.

Speaking with detectives again in 2008, Ridgway told investigators he left another body near Malvar. That body -- Marrero's body -- was found by three teens exploring the wooded hillside on Dec. 21.

"With proof that her body was left in close proximity to that of Maria Malvar … Becky Marrero is no longer the victim of an uncharged Green River homicide," King County Detective Scott Tompkins said in court documents. "She was murdered by Gary Ridgway."

Marrero was one of six women who disappeared in the early '80s whom investigators long suspected were victims of the Green River Killer. Ridgway also told detectives he's certain he killed Keli McGinness, Kase Lee and Patricia Osborn, but their remains were never found to corroborate his claim.

Mary Marrero said she doesn't believe Ridgway has ever told all he knows about the locations of his remaining victims. She said the killer is keeping them as "trophies," and that he should be put to death.

"What does it take to get the death penalty in the state of Washington?" Marrero asked rhetorically.

"He knows where all his victims are and where to find them. … It makes me sick to my stomach that he beat the system."

Ridgway pleaded guilty Friday in King County Superior Court at the Norm Maleng Regional Justice Center. He'll be returned to Washington State Penitentiary in Walla Walla.